Heat exchangers of hollow construction



Jan. 10, 1967 1 TRANEL ET AL 3,297,082

HEAT EXCHANGERS OF HOLLOW CONSTRUCTION Original Filed May 9; 1961 5 Sheets-Sheet l IFIIGWII INVENTORS LESTER J. TRANEL BY ELMER H CARR ATTORNEY Jan. 10, 1967 L. J. TRANEL ET AL HEAT EXCHANGERS OF HOLLOW CONSTRUCTION 5 Sheets-Sheet 2 Original Filed May 9, 1961 L W W WW TA NR J R ET @W V .7 mH CAUM R mm EL U L E /p wfiz 5 M 2 1 4 B 2 5 uwm WY 5 l B 5 u 6 m. 1% H 5 W4 F. H

Jan. 10, 1967 1 TRANEL ET AL 3,297,082

HEAT EXCHANGERS OF HOLLOW CONSTRUCTION Original Filed May 9, 1961 5 Sheets-Sheet l IFIG=9 3 3 L\\-\ is L l\ Ik filzafi aa lf $28 v INVENTORS'. LESTER Jw TRANEL BY ELMER H. CARR [F H (i) n M) Jan. 10, 1967 L. J. TRANEL ET AL HEAT EXCHANGERS OF HOLLOW CONSTRUCTION 5 Sheets-Sheet 4 Original Fi led May 9, 1961 PUG-Ill IFIIG 112 INVENTORSI Jan. 10, 1 967 L. J. TRANEL ET AL 3,297,032

HEAT EXCHANGERS OF HOLLOW CONSTRUCTION Original Filed May 9, 1961 5 Sheets-Sheet 5 55 y I INVENTORSI I I LESTER J.TRANEI 56 62 56 6| BY ELMER H. CARR ATTORNEY United States Patent Office 3,297,.ii82 Patented Jinn. Id, 1967 3,297,082 HEAT EXCHANGERS F HOLLGW CUNSIRUCIIGN Lester .I. 'Iranel, St. Louis, Mo, and Elmer H. Carr, Brighton, Iil., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia Original application May 9, 196 Ser. No. 108,862, new Patent No. 3,206,839, dated Sept. 21, 1965. Divided and this application May 18, 1965, Eer. No. 474,193 I Claim. (Cl. 165-470) This application is a division of copending application Serial No. 108,862, filed May 9, 1961, now U.S. Patent No. 3,206,839, issued September 21, 1965.

This invention relates to the fabrication of hollow articles, and more particularly to sheet metal heat exchangers.

In the manufacture of metal or plate-like heat exchangers, it is often desirable to utilize said heat exchangers in conjunction with one or more additional sheet metal structures or plates for various applications.

Typical of such applications are those in which it is often found desirable to have the heat exchanger formed with a duct-like structure defining a secondary passage for a heat transfer medium disposal externally of the heat exchanger. An example of such a structure is a duct for transmission and circulation of the air found in the food compartment of conventional refrigerators, with the heat exchanger forming the evaporator panel employed for the cooling of the air.

In other applications, it is often desirable to combine the heat exchanger and the sheet metal structure in the form of structural panels for use as wall separations in which the heat exchanger serves to condition the air adjacent thereto, as, for example, radiant heating of rooms of a home or for cooling the components of various structures, such as the interior of truck bodies.

Heretofore, the adaption of sheet metal heat exchangers for such uses has involved the cutting, and the like, of a plurality of individual units or components with or without forming, assembling them together and then joining them together by welding, riveting and the like. However, irrespective of the manner in which these components have been assembled, the method involves the disadvantage of requiring the handling of large numbers of components in the assembly of the components and the proper relationship and register with each other. Further, such methods require the use of excess and additional material in the form of welds or rivets which appreciably increase the weight and cost of the desired fabricated unit.

Accordingly, it is an object of this invention to provide a novel heat exchanger having increased heat transfer capacity.

It is another object of this invention to provide a novel sheet metal heat exchanger having formed therewith an integrated duct extending along a face of said heat exchanger adapting it for use as a forced-convection-type heat exchanger.

It is still further the object of this invention to provide a novel sheet metal heat exchanger adapted for use as a structural panel.

Other objects and advantages of this invention will become more apparent from the following description and drawings in which:

FIGURE 1 is a partial View in perspective illustrating an assembly of component sheets in accordance with one embodiment of this invention;

FIGURE 2 is a partial view in perspective of a section illustrating a sheet component treated in accordance with the said embodiment of this invention;

FIGURE 3 is a partial View in perspective illustrating a section of the opposite face of the component depicted in FIGURE 2;

FIGURE 4 is a partial plan view in section illustrating an assembly of said components incorporating the embodiment depicted in FIGURE 2;

FIGURE 5 is a sectional view taken along lines VV of FIGURE 4;

FIGURE 6 is a plan view, partly in section, illustrating one mode of treating the component depicted in FIG- URE 2;

FIGURE 7 is a partial View in elevation illustrating the unification of the assembly of components depicted in FIGURES 4 and 5;

FIGURE 8 is a section View taken along lines VIII- VIII of FIGURE 7; ing one mode of treating the component depicted in FIG- URE 8 after partial distention thereof;

FIGURE 10 is a section view illustrating the section of FIGURE 9 having the outer components thereof disposed in their desired spaced relationship;

FIGURE 11 is a sectional side view illustrating the section of FIGURE 10 in its fully distended form;

FIGURE 12 is a sectional side view illustrating a modification of the embodiment depicted in FIGURE 11;

FIGURE 13 is a partial plan view in section illustrating a modified assembly of components for obtaining the embodiment depicted in FIGURE 11;

FIGURE 14 is a sectional view taken along lines XIV XIV of FIGURE 13;

FIGURE 15 is a partial plan view in section illustrating an assembly of said components for obtaining another embodiment of this invention;

FIGURE 16 is a sectional View taken along lines XVI-XVI of FIGURE 15;

FIGURE 17 is a sectional side view illustrating the embodiment of FIGURES 15 and 16 after unification and distention; and

FIGURES 18 and 19 illustrate a still further embodimerit of this invention in an assembled form and in a corresponding partially distended form.

Generally speaking, this invention comprehends the use, between a pair of outer sheet metal structures, of at least one inner sheet with at least one of the outer sheets formed or adapted for such forming by selective unification of adjacent portions of two or more superimposed component sheets, so as to define between. the component sheets a pattern of unjoined areas corresponding to a desired system of fluid passages. In accordance with this invention, the inner sheet is treated to provide a plurality of appropriate slits by appropriate cutting of this inner sheet along a plurality of speciai lines extending across this sheet in a direction parallel to a pair of opposite edges thereof, so as to divide the inner sheet into a plurality of sections corresponding to the number of crossmembers desired between the outer sheet metal structures.

In accordance with this invention, the cutting or slitting of the inner sheet will terminate sufliciently short of one or more edges, transverse the referred-to opposite edges, to provide an unslit marginal portion on the inner sheet between this edge or edges and the slit portion of the inner sheet. Thereafter, stop-weld or weld-inhibiting material is applied to both sides of these sections and the portions thereof designed to form the desired crossmembers between the outer sheet metal structures. Subsequently, the inner sheet is assembled between the two outer sheet metal structures and the entire assembly pressure welded together in the adjacent areas of its components, not separated by stop-weld material, so as to form a unitary structure.

The outer walls or structures of the assembly are then spaced apart into their desired spatial relationship by any suitable means well-known in the art, such as mandrels, vacuum platens and by fluid inflation, under suflicient force to obtain the desired spatial relationship and to erect the sections of the inner sheet, between adjacent slits, into the desired cross-members extending from and between the opposite walls of the resultant panel.

In accordance with this invention as will be pointed out herein, various shaped integral cross-members can be formed between opposed Walls of the resultant panel. For example, the stop-weld material can be applied to each section of the slit inner sheet in a pattern provided so that, in the portions of all sheets adjacent one section of the inner sheet, the band of material between one pair of adjacent surfaces will be in adjacent and overlapping relationship to a band of the weld-inhibiting material between a successive pair of adjacent surfaces. By this pattern, the portions of each section adjacent diagonally opposed edges, defining them, become welded to adjacent sheets with the portions of the sections between the overlapping portions of the applied bands of weld-inhibiting material forming, upon pressure welding and distention, the desired cross-members integrally extending etween the opposed walls of the resultant panel.

Referring to the drawings, FIGURE 1 illustrates a metal sheet component ll, such as AA 1100 type aluminum alloy or AA 6061 type aluminum alloy clad with AA 1100 type aluminum alloy, which is to be assembled between a pair of outer sheet metal structures and from which com ponent sheet 1, the desired number of cross-members are to be formed to integrally connect with and extend between the walls of the desired panel. In accordance with one embodiment of this invention, one of the outer sheet metal structures is comprised of an outer component sheet 2, whereas the other outer sheet metal structure is comprised of sheet metal components 3 and 4 between which is interposed a pattern of weld-inhibiting material 5, which is applied to one of the adjacent faces of this pair of sheets, corresponding to the system of passages desired in the ultimate panel. The means of application of this pattern 5 of weld-inhibiting material may be applied in any conventional manner, as, for example, in accordance with the teachings of US. Letters Patent No. 2,690,002 granted on September 28, 1954 to L. H. Grenell.

In addition, the invention contemplates adapting the inner component sheet I, see FIGURE 2, for the formation of the desired cross-members by providing by any well-known means a plurality of spaced slits 6 necessary to divide the inner component sheet ll into sections '7 corresponding to the number of cross-members desired between the walls of the ultimate panel. These sections 7 are obtained by slitting the inner component sheet I along a plurality of lines which are spaced from each other and which extend parallel to the pair of opposite edges 8 and 9 of the component sheet 1. Generally, these slits will extend in a direction which will be longitudinal with the direction of subsequent rolling with the slit parallel to the lateral edges of sheet 1. However, in accordance with this invention, the slitting will be terminated short of an edge 10 which extends transverse edges 8 and 9 so as to leave an unslit marginal portion 11 on inner sheet 1, between edge 10 and the slit portions of sheet 1. It is also contemplated that the slitting may be terminated short of the edge opposite to edge llll, so as to leave an additional unslit marginal portion on sheet 1 wherein the slits form perforations or slots through this sheet. As will be understood, the selection of the specific manner of slitting will be dependent on a specific application to which the panel is to be put. As will also be understood, the slitting may be accomplished by various means well-known in the art, as, for example, by rotary cutting tool 12, such as a saw, as depicted in FIGURE 6.

After the provision of slits 6 on sheet 1, if necessary, the sheet may be given any suitable treatment such as a preliminary cleaning or wire brushing of the fraying surfaces in order to adapt the sheet for unification by welding. Thereafter, each of sections '7 of sheet I are coated with a suitable weld-inhibiting material, such as graphite in water glass, on both sides of the sections. As illustrated in FIGURES 2 and 3, duplicated on each of the sections are patterns of the weld-inhibiting material applied as bands 13 and 14 on both sides on each section. As shown the bands of weld-inhibiting material 13 and 14 are applied so that they will be disposed adjacent diagonally opposed lateral edges defining each of the sections. As can be seen, the coating of weld-inhibiting material is applied to edge of section '7 so as to provide bands 15 and 15 free of weld-inhibiting material on the opposite sides of and disposed adjacent diagonally opposed lateral edges of each of the sections.

In the specific embodiment described, the bands of weld-inhibiting material 13 and M, on each of the sections of sheet I, are in staggered and overlapping relationship with the parts of each section between the overlapping portions of the weld-inhibiting material corresponding to the cross-members desired between opposed walls of the ultimate panel as depicted in FIGURE 5. In this embodiment, the marginal portion ll of inner sheet 1 is shown to be uncoated with the stop-weld material. It is to be understood that this marginal portion 11 may be coated with this material if this portion is not desired to be welded during subsequent welding operations particularly where it is desired to utilize mechanical means for distention of the ultimate panel.

Subsequent to the application of the weld-inhibiting material, component sheet l is assembled between a pair of inner sheet metal structures, one comprised of component sheet 2 and the other of the pair comprised of component sheets 3 and 4, to form an assembly of components 17 illustrated in FIGURES l, 4 and 5. It is to be understood that the spacing and thickness of the various components in FIGURE 5 is illustrated in exaggerated form to denote more clearly the application of weld-inhibiting material between adjacent surfaces of component sheets 1, 2, 3, and 4, and each of the sections of the component of inner sheet 1. Generally, the thickness of the weld-inhibiting material employed will be of the order of 0.001 of an inch which will be the distance of the spacing between the various component sheets. However, as will be obvious, smaller or greater thicknesses of Weld-inhibiting material may be employed between the various component sheets. In addition, to illustrate the general thicknesses of the component sheets, one unit of this embodiment of the invention was obtained with sheets I, 2, 3, and 4 having thicknesses, respectively, of 0.169, 0.127, 0.127 and 0.17 of an inch. Also, although in this embodiment, each of sections 7 have been illustrated as being of equal width, it is to be understood that Where a panel of angular dimensions is desired the width of the sections of component sheet 1 would be progressively decreased.

After assembly of the various components as illustrated in FIGURES l, 4 and 5, they may be suitably secured together against separation in any appropriate manner, not shown, as by spot welding to the corners of the stack, or by any other suitable manner.

Although specific aluminum alloys have been referred to in the foregoing example, it is to be understood that a variety of metals may be employed depending not only upon economic consideration, but particularly upon the specific application to which the ultimate panel is to be put. Thus, the ultimate panel of this invention can be made from other aluminum alloys including heat treatable alloys, copper alloys, titanium, zirconium, steel, or similar alloys. Similarly, any weld-inhibiting material capable of preventing welding of juxtaposed surfaces may be substituted for a specific weld-inhibiting material described above.

Also, the metal sheets employed may be of any combination of metals for any desired application. For example, if the panel is to be employed as a structural panel in the fabrication of walls for buildings, it is generally preferred that the panel be not only lightweight, but, in

addition, resistant to the elements. Similarly, a lightweight panel is also desired where the panel is to be employed, as indicated above, as a forced-convection-type heat exchanger for application in refrigeration systems. In this last application, the crossmembers extending between the outer sheet metal structures function to extend the surfaces of the evaporator for heat transmission, and wherein the open areas between the outer surfaces serve as ducting for movement of air within a refrigerator; and as will be understood the system of passageways within one or more of the outer wall structures serves to provide the desired network of passages for the flow of the refrigerant required for cooling the air in a refrigerator. in such applications, it is readily seen that aluminum is not oniy suitable but preferred since it is both relatively light in weight and resistant to oxidation.

However, if the resultant panel is intended for use as a structural panel in applications which require it to withstand any type of a severe loading force, it is readily seen that the panel will be of heavier gauge or of other metal or of a combination of the two. Thus, if the panel is intended for heavier application such as a floor bed supporting heavy weights, the panel may be formed of steel and the like. In addition, Where the panel is intended for application for forming bodies of refrigerated trucks and the like, it will be understood that the panel may be formed of steel, whereas where the panel is employed for the side Walls it may be formed of aluminum.

Similar variables also apply with respect to the specific gauges of the metals employed, since the thickness of the metal will vary according to the application intended for the final fabricated unit. Accordingly, the gauges of the components may be selected to give a uniform crosssectional thickness in all of the components, or any desired variation in thickness between the outer walls and inter-connecting webs or legs which the cross-members form extending between the outer walls. In like manner, the components may be selected from various combinations of metals to provide physical properties in the outer surfaces distinguishable from the physical properties in the cross-members between them as, for example, to provide elongation with sufficient retention of hardness in the cross-members.

Subsequent to securing the various sheet components together against separation, the pack 17 is then ready for pressure welding together of the components in accordance with conventional practices. Typical practices by which the panel may be welded together are set forth in the wellknown process for fabricating hollow panels such as refrigerator heat exchangers and the like disclosed in the aforesaid U.S. Letters Patent to Grenell, No. 2,690,002.

In accordance with conventional practice, the secured assembly of components may be heated in a suitable furnace to appropriate pressure welding temperatures, for example about 900 F. for components of aluminum alloys. Thereafter, the pack is rolled between a pair of mill rolls 1% and 19, see FIGURE 7, to effect sufficient reduction, such as about 65% for aluminum alloys, necessary to pressure weld all-adjacent areas in the stack not separated by weld-inhibiting material. This pressure welding results in a substantially complete erasure of the interfaces between the components by inter-dispersion of the grains between adjacent surfaces. The resultant juncture is usually characterized by tensile strength equal to that of other seamless regions of the blank. As will be understood, the amount of reduction required to effect pressure welding will vary with the particular combination and the physical properties of the various combinations of component sheets employed. Generally, a reduction of the order of 35% will accomplish pressure welding of adjacent surfaces not separated by weld-inhibiting material. However, it will be understood that lower or higher percentage reductions may be sufficient or required with different metals and/or different temperatures employed in the pressure welding operation.

By reference to the resultant blank 2d of FIGURES 7 and 8, it can be seen that portions of each of the sections of the inner component sheet 1 are welded to the outer sheet metal structures adjacent to each side of sheet 1 with the areas of the adjacent surfaces separated by weldinhibiting material remaining unwelded to provide laminations within the blank in accordance with the pattern of weld-inhibiting material utilized. Accordingly, the band 15 devoid of weld-inhibiting material applied on one side of the sections of component sheet 1 results in a pressure welding of this portion of the sections to the outer sheet metal structure, comprised of sheet 2 adajacent thereto, as at 21, whereas the adjacent surfaces between sheet I and sheet 2 separated by weld-inhibiting material, results in laminations 22 between them. Similarly, the sections of inner component sheet I are pressure welded at 23 to component sheet 3 adjacent the other side of sheet 1 while leaving unwelded portions defining the laminations 24. Similarly, portions of the adjacent surfaces between component sheets 3 and 4 of the other outer sheet metal structure become welded at 25 in their areas not separated by weld-inhibiting material, whereas those areas separated by the material result in a pattern of laminations 26 extending in a pattern corresponding to the desired system of fluid passages.

As indicated in FIGURE 8, during pressure welding portions of component sheets 2 and 3 may be extruded into the slots formed by the slitting. Where severe reductions are employed in a pressure welding operation, the extruded portions of component sheets 2 and 3 may be lightly tacked or welded to the surfaces defining the slots or perforations provided in inner component sheet 1. Such tack welding across or within the slots will produce welds of relatively much weaker strength compared to :the welds obtained between other adjacent surfaces of the various component sheets. In subsequent separation or spacing apart of the outer sheet metal structures of pressure welded blank 20, the force employed in such separation will literally tear apart the weak weld formed in the slots wtihout in any manner affecting the desired weld between the various component sheets. If desired, and preferably, the formation of these weak welds across and in the slots can be prevented by the application of a smail amount of weld-inhibiting material on the surfaces of the slot or by filling the slots with weld-inhibiting material prior to pressure welding.

By application of the weld-inhibiting material to the inner component sheet ll, as secttionalized in accordance with this invention, the component sheets of the stack 17 become selectively welded together to form a plait or a plaited portion 27 of an embryonic or undeveloped cross-member 255, see FIGURE 9, extending between and integral with the outer walls 29 and 30 of the resultant unit 31. Thus, as can be seen, the particular pattern of weld-inhibiting material employed adjacent the inner component sheet 1 and between component sheets adjacent thereto defines and forms a continuous section of an unwelded portion of metal, comprising the plaited portion 27, folded over upon itself. During subsequent distention, these plaited portions are caused to unfold to form the desired cross-members 2% each of a unitary construction of substantially uniform thickness and integrated at its opposite ends to the walls of the structural panel.

After pressure welding, the pressure welded blank 20 is ready for distention to separate the outer sheet metal structures 29 and 39 from each other. However, if desired, prior to distention, the blank 20 may be softened in any appropriate manner as by annealing for removing the effects of mechanical working, and thereafter cold rolled to provide a more uniform thickness or to final gauge, and again annealed. After treatment to obtain the specific conditions desired in the pressure welded blank, the outer walls 29 and 30 may be separated into the spacing desired between them by driving into the laminations a suitable mandrel, not shown, whose dimensions are graduated from a thin opening edge into a configuration corresponding to the configuration of the openings 32 formed in the resultant panel 33.

Alternately, any other suitable means may be employed within or to the surfaces of the pressure welded blank 20 to separate the outer walls and to unfold the plaited portions of cross-member 28. For example, where the separation of the outer walls is desired to be accomplished with fluid pressure, the assembly of components in stack 17 may be adapted to provide a fluid tight pressure welded blank adapted to contain a fluid under pressure in accordance with the teachings set forth in US. Letters Patent No. 2,766,514 granted on October 16, 1956, to R. F. Adams, or in accordance with the teachings set forth in co-pending application Ser. No. 823,960 filed by (Vt 1118M? C. Johnson on June 30, 1959, now US. Patent No. 3,111,- 747, issued November 26, 1963.

Distention of the panel in this latter manner can be utilized to advantage by simultaneous expansion of the pattern of laminations 26 into the desired system of fluid passages 35, see FIGURE 11, simply by insertion of an inflation needle, not shown, into an inlet lamination at an edge of the blank 20, which inlet lamination may be provided by an extension 34. of the pattern of stop-weld material applied to the component sheet 4. Such simultaneous expansion may be readily obtained by simple manifolding of the fluid injecting means utilized in expanding the laminations 26, contained in wall 30 and the fluid injecting means employed for separating the walls 29 and 30 into the desired spatial relationship between them. This expansion of the fluid passages 35 and erection of the cross-members 28 between outer wall structures 29 and 30 of the pressure welded blank 20 may be accomplished without aany external restraint against expansion or the blank may be distended between opposed rigid platens or surfaces, with the specific configuration of the embodiment illustrated in FIGURE 11 attained by an expansion without use of any external restraint against it. However, it will be noted that irrespective of use or non-use of restraint against expansion, the passages become distended so that a portion of the walls of said passages which are adjacent to the other outer wall structure are bulged in a convex configuration. In other words, the walls of the fluid passages 35 which remain disposed within the panel have an elliptical configuration.

In addition, it will be understood that the special relationship between outer walls 29 and 30 may be such that no elongation is induced in cross-members 28, or to a spatial relationship which will cause the cross-members to elongate. As a result of the manner by which panel 33 is obtained upon separation of the outer walls to the desired spatial relationship, these walls will have in each adjacent pair of laterally extending flanges a portion 36 of one extending beyond and further than the other. In order to provide a uniform panel the extending portion 36 of the overlong flange may be suitably trimmed along line 37.

FIGURE 12 illustrates a modification 33' of the preceding embodiment in which both outer walls 29 and 30 are provided with a system of fluid passages 35 and 35. This additional system of passageways may be obtained by applying to the external face of said component sheet 2 a duplicate of the pattern of weld-inhibiting material 5 applied to said component sheet 4'. or, where desired, a diiferent pattern of the system of fluid passages desired, and then superimposing an additional metal sheet on component sheet 2. In addition, this modification depicts the external configuration of passages 35 and 35' when the pressure welded blank for this modification is expanded between opposed rigid platens or surfaces. In addition, it will be noted that the walls of the passages of 35 and 35' disposed within panel 33 have a convex or elliptical configuration.

Although the preceding embodiments included the fabrication of a system of fluid passages in one or more of the outer wall structures simultaneously with the fabrication of the desired panel itself, FIGURE 13 illustrates an additional modification wherein one of the outer sheet metal components 38 is initially formed by unification of two or more component sheets together about a fluid passageway pattern of weld-inhibiting material 39 prior to placement in the assembly or stack 43. The fabrication of the internally laminated outer wall structure 30 may be obtained by any of the well-known methods and particularly by the teachings set forth in the aforesaid U.S. Letters Patent to L. H. Grenell.

FIGURES 1517 illustrate a further modification of this invention by which is obtained a three walled structure with each wall interconnected by integral cross-members with the inner metal wall 41, see FIGURE 17, disposed between two outer walls 42 and 43 with only the inner wall 41 provided with a system of fiuid passages 44. Further, this modification is obtained with the marginal portions of the sheet metal components abutting the pair of common edges 45 and 46 integrated together as by welding. As will be observed in FIGURES 15 and 16, this modification is attained by superimposing a sheet metal component 47 and 48 adjacent and opposite each face of an internally laminated wall component 49 with an inner sheet 5%) interposed between component sheets 47 and 49 and an inner sheet 51 interposed between component sheet 4-8 and 49. As discussed above, each of the inner sheets 50 and 51 are suitably slit and coated with stopweld material in accordance with the preceding embodiments. Unification of the marginal portions adjacent to common edges 4-5 and 46 may be obtained as discussed above in accordance with the aforesaid U.S. Letters Patent granted to R. F. Adams or by the teachings set forth in the aforesaid co-pending application of Wallace C. Johnson, now US. Patent No. 3,111,747, issued November 26, 1963. Unification of the various components and distention of the resultant blank between opposed rigid surfaces results in a resultant blank such as 52 illustrated in FIG. 17.

FIGURES l8 and 19 illustrate still another modification of the preceding embodiments in which two identical inner component sheets 53 are employed between two outer sheet metal structures 54 and 55 with one of the structures being internally laminated at 56 in accordance with the system of fluid passages desired in the ultimate panel. As will be observed, each of the inner component sheets are divided into a plurality of sections by slitting at 57 with a pattern of weld-inhibiting material applied to provide bands of it at each successive pair of adjacent surfaces at successive alternate edges defining the sections of the inner component sheets. This modification results in a panel 58 having interconnecting cross-members 59 between outer walls 60 and 61, with the system of laminav tions 56 in the wall 61 remaining in their undistended form. The panel is shown in partially distended form as panel 33' in FIGURE 11 to illustrate the unfolding of the plaited portions formed as a result of this modification, and to illustrate the attainment of flanges 62 which are projected from the sides of the cross-members 59. The provision of the flanges 62 provides additional advantage when the unit is desired to be employed as a heat exchanger, since these flanges can be made to extend the surfaces of the heat exchanger so as to serve as fins for the transmission of heat from and into heat exchanger mediums employed in the tubular cross-sections 63 which are formed between the outer walls 60 and 61 and the tubular cross-sections which will be formed upon distention of the laminations 56.

. Although the invention has been described with reference to specific embodiments, materials and details, various modifications and changes within the scope of the invention will be apparent to one skilled in the art and are comtemplated to be embraced within the invention.

What is claimed is:

A hollow article of the character described, comprising (A) at least two separate sheet metal structures hav- 9 10 ing adjacent faces in opposed relationship to each ends to said structures, said cross-members being inteother, at least one of said structures comprised of at gral with said joined portions. least two superimposed metal sheets selectively joined together at their adjacent faces to define between said References Cited y the Examine! sheets a pattern of internally unjoined portions cor- 5 UNITED STATES PATENTS responding to a desired system of fluid passages,

(B) said unjoined portions being distended so as to ghnson 12 form said passages with a portion of the walls of said euer passages which are adjacent to the other of said FOREIGN PATENTS structures being of a bulged configuration, and 10 220,857 3 /1959 Australia (C) spaced cross-members coextending with each other extending from and substantially perpendicular to MEYER PERLIN, primary Examiner the plane of said structures, each of said cross-members being of a unitary construction of substantially ROBERT O LEARY Exammer' uniform thickness and integrated at its opposite 15 M. A. ANTONAKAS, Assistant Examiner.

UNITED S'lA'lES mrnnr UEElCE CERTIECATE l COREC'HON Patent No a 3 ,297 ,082 January 10 1967 Lester J. Tranel et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 1, line 37, for "adaption" read adaptation column 2 line 14 strike out "ing one mode of treating the component depicted in" and insert instead FIGURE 9 is a section side view of the blank of column 6, line 12, for "adajacent" read adjacent line 47 for secttionalized" read sectionalized column 7, line 33, for "aany" read any line 45, for "special" read spatial Signed and sealed this 20th day of August 1968.

(SEAL) Attest:

EDWARD l. BRENNER Commissioner of Patents Edward M. Fletcher, 11'.

Attesting Officer 

